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Re: Why do I keep fouling plugs? (idling issue as well) [Re: 68HemiB] #367987
07/06/09 03:08 PM
07/06/09 03:08 PM
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Florida
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Re: Why do I keep fouling plugs? (idling issue as well) [Re: 68HemiB] #367988
07/06/09 04:59 PM
07/06/09 04:59 PM
Joined: Sep 2007
Posts: 5,037
hi
sharpie Offline OP
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Quote:

You went to the trouble of installing a fuel pressure gauge, and are now pretty anxious to ignore or explain away what it's telling you.

If the gauge sees 15psi, so does the carb, whether it is smooth or spiky.

Running without the gas tank cap for a period of time would rule out the possibility of a pressurized gas tank.

That would take one thing off the table.




Hmm. I guess I wouldn't rule out pressure in the tank, but I thought it a little unusual that a fuel pump would be pressurizing fuel at that different a rate?

I should mention another symptom. I originally just thought it was a matter of using parts of less quality, but maybe it does indeed point to a pressurizing of the fuel tank?

Here's a picture of where the fuel filter sits:



Ignoring the dots above the 'A', look at where the red arrow points. When I had a single hose clamp on the line (a fingered one like this), I once had fuel spraying out of the rubber line from the left side of that rubber piece toward the passenger side fender well.

I thought this a matter of using bad parts, so I increased the quality with a screw-type hose clamp (like this). Alas, a single one didn't hold, and I was forced to put a second screw-type clamp on there, where the blue arrow labeled 'B' points.

I really thought it was some incompatibility with the stainless line (which is double-flared correctly) and the rubber hose that came from the filter's packaging. But maybe it points to a pressurized fuel tank?

Re: Why do I keep fouling plugs? (idling issue as well) [Re: sharpie] #367989
07/06/09 08:35 PM
07/06/09 08:35 PM

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I had a brand new Carter Mechanical fuel pump that would fluctuate pressure as your's is doing, it would go as low as 3 psi to as high as 15 psi. I ended that by installing a new electric pump with regulator, no more fluctuations in psi and no more running issues.

Re: Why do I keep fouling plugs? (idling issue as well) #367990
07/06/09 09:00 PM
07/06/09 09:00 PM
Joined: Sep 2007
Posts: 14,889
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Supercuda Offline
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AT IDLE who cares if the metering rod pistons are bouncing up and down. Nothing is being drawn thru the main circuit, they can dance an Irish Jig all day long and it won't affect IDLE mixtures.

Heck, pull them out and see if you notice a change at all.

Now if we were on the cruise circuit tooling about, yeah, but Idle no.


They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.
Re: Why do I keep fouling plugs? (idling issue as well) [Re: sharpie] #367991
07/06/09 09:05 PM
07/06/09 09:05 PM
Joined: Nov 2003
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Lincoln Nebraska
RapidRobert Offline
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Quote:

I'm thinking that this should/could be corrected in a much simpler and cheaper manner.


disconnect/plug the fuel pump & suspend a small gas container(w a bottom outlet) from the hood latch & gravity feed the carb & throw in a new set of plugs. You'll find out real quick if it was a actual psi problem


live every 24 hour block of time like it's your last day on earth
Re: Why do I keep fouling plugs? (idling issue as well) [Re: sharpie] #367992
07/06/09 09:35 PM
07/06/09 09:35 PM
Joined: Dec 2007
Posts: 7,759
So Cal
HealthServices Offline
Why would you even post that?
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Quote:

I don't think it's pressure. I think the fuel pressure gauge is going wild because there's air in the line.




My Fuel presure goes to 0 when it sucks air. It is a electric pump.

Quote:

but how could a mechanical fuel pump possibly be getting that much pressure built up?




A electric pump may have a 1/16 of a horsepower driving it. Why is it that you don't think a engine that is making 300 horse cannot drive the fuel presure of a mechanical pump to over 7 psi?


Allen Here's a novel idea, let's not throw a bunch of parts at the car hoping it will fix the problem and instead spend a little time diagnosing it first. Life was a little easier when I was just a wrench.
Re: Why do I keep fouling plugs? (idling issue as well) [Re: HealthServices] #367993
07/06/09 10:20 PM
07/06/09 10:20 PM

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Quote:

Quote:

I don't think it's pressure. I think the fuel pressure gauge is going wild because there's air in the line.




My Fuel presure goes to 0 when it sucks air. It is a electric pump.

Quote:

but how could a mechanical fuel pump possibly be getting that much pressure built up?




'S not how electric pumps work. The engine, so to speak, only "cocks" the mechanical pump. The pump stroke is driven by the SPRING in the pump, and is also what determines pump pressure. That's why when you run an electric through a mechanical, the overall pressure doesn't go up---the electric simply drives the pump arm away from the cam, and the pump "floats"

A electric pump may have a 1/16 of a horsepower driving it. Why is it that you don't think a engine that is making 300 horse cannot drive the fuel presure of a mechanical pump to over 7 psi?



Re: Why do I keep fouling plugs? (idling issue as well) [Re: Supercuda] #367994
07/06/09 10:33 PM
07/06/09 10:33 PM

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Quote:

AT IDLE who cares if the metering rod pistons are bouncing up and down. Nothing is being drawn thru the main circuit, they can dance an Irish Jig all day long and it won't affect IDLE mixtures.

Heck, pull them out and see if you notice a change at all.

Now if we were on the cruise circuit tooling about, yeah, but Idle no.





Actually they can. He's talking about poor idle, at rpms at or above 850, which "could" be into the transition area, especially if camshaft, vacuum leak, whatever, is causing more than normal throttle plate opening, who knows at this point?

Fuel for idle and transition comes through the main jet/ well area, and disturbances such as "bounching pistons" can certainly affect the idle passage fuel flow.

Re: Why do I keep fouling plugs? (idling issue as well) #367995
07/06/09 11:20 PM
07/06/09 11:20 PM
Joined: Apr 2005
Posts: 12,271
Overpriced Housing Central
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I've got a LM1 for sale if you are looking for one.

Haven't read the entire thread, but, start with the basics, timing, etc.

Re: Why do I keep fouling plugs? (idling issue as well) [Re: RobX4406] #367996
07/06/09 11:59 PM
07/06/09 11:59 PM
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Montana
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These carbs hate pressure. I have had to put a dial type regulator on every vehicle with an edelbrock or carter. Stock pumps can vary on the pressure they put out. On one GM pickup I had there was 9 psi out of the pump. Ran horrible because it would bypass the needle and seat. Stock mechanical pump in my Demon was around 8 psi. After the regulator they ran great.

Re: Why do I keep fouling plugs? (idling issue as well) [Re: Posest] #367997
07/07/09 08:38 AM
07/07/09 08:38 AM
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Posts: 15,487
Florida
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seems the line and rubber piece is 2 diff sizes if it takes 2 clamps to seal it,looks like 3/8 rubber on a 5/16 line,5/16 hose will be real tight on the 5/16 line and the finger type clamp you show will work fine for holding

I have had better luck with the filter down by the pump and not up there were you got it

it will get a lot of heat right there,IMO

not to mention, the fire hazzerd

small elect fuel pump in the back by the tank and a fuel regulater will take care of it

I run the elect pump into a HPG1 filter then up to a regulator and then to the inline eddie filter on the eddie duel feed metal line on the eddie carb,once I cut it back to a steady 3 lbs it stoped flooding,rough idle,poor hot starts,fouling plugs


Re: Why do I keep fouling plugs? (idling issue as well) [Re: scratchnfotraction] #367998
07/07/09 12:46 PM
07/07/09 12:46 PM
Joined: Sep 2007
Posts: 5,037
hi
sharpie Offline OP
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Well, I did nothing special yesterday, and wouldn't you know it, when it started, it had no issue. It did take a couple crank sessions to get it started though. I try not to press the accelerator pedal more than once before it starts, so I don't know if there's enough gasoline in there.

I have no idea what this intermittent problem is, but it's sure stumping me, and will never come back when I want it to. It makes it very hard to diagnose.

Re: Why do I keep fouling plugs? (idling issue as well) [Re: sharpie] #367999
07/07/09 02:59 PM
07/07/09 02:59 PM
Joined: May 2003
Posts: 15,487
Florida
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scratchnfotraction Offline
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boy! do I know what ya mean

keep plugin away,it will come around sooner or later


Re: Why do I keep fouling plugs? (idling issue as well) [Re: sharpie] #368000
07/08/09 06:17 AM
07/08/09 06:17 AM
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Montana
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FuryUs Offline
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What did the fuel pressure gauge say when it was running right?

Re: Why do I keep fouling plugs? (idling issue as well) [Re: FuryUs] #368001
07/08/09 12:47 PM
07/08/09 12:47 PM
Joined: Sep 2007
Posts: 5,037
hi
sharpie Offline OP
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between 6psi and 7psi.

Re: Why do I keep fouling plugs? (idling issue as well) [Re: sharpie] #368002
07/08/09 02:14 PM
07/08/09 02:14 PM
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Florida
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IMO,thats too much for the eddie carb

I have a brand new set of off road needles and seats with the spring to load the needle and hold it on the seat off roading

you want those to try in it?


Last edited by scratchnfotraction; 07/08/09 02:19 PM.
Re: Why do I keep fouling plugs? (idling issue as well) [Re: scratchnfotraction] #368003
07/10/09 01:06 PM
07/10/09 01:06 PM
Joined: Sep 2007
Posts: 5,037
hi
sharpie Offline OP
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Ain't this a....

So fun story about testing out these theories last night. My buddy Russell finally gets back from his vacation, so he comes on over to lend a set of hands and eyes.

We make sure everything's ready, the key is in the gas cap and such, and he says crank it. So I crank and it fires up, and it even fires up really rough! FINALLY I can test the gas cap and fuel pressure theories!

As it's idling in a rough manner, probably at 600RPM, I run to the gas cap, turn the key, and twist it loose. It's now venting, and I hear no change in the engine. Alright, check tank venting issues off the list, or so I suppose.

We sat there listening to the engine struggle. It had between 3 and 5hg of vacuum, the fuel pressure gauge was wobbling between only 5-7lbs this time, but oil pressure, water temp were fine and I had enough fuel in the tank (6-8gal). To test further, we decided to give it some gas. He pulled back the throttle lever about 1/4" to bring the speed up to maybe 1500 then let it go quickly. But the engine reaction wasn't instant. It wasn't even close. It took about 1/2 second for the engine to register it was getting a throttle command, and then it would rev for how long you had the lever depressed. It was a weird phenomenon.

Russell has the wheels turning in his head and asks for a spray bottle of water. He has me get a spray bottle from inside, and while I'm there (about 20 seconds), I was told it 'kind of backfired and then died.' So the engine had been running maybe 5 minutes at this point, and was pretty warm, maybe even warmed up to the point that it had opened the thermostat, but I wasn't sure.

So he and I checked some lines, made sure the carb was seated tight, etc, but didn't end up changing anything because nothing seemed to be out of order. What's important to note was that we definitely didn't change anything here, and also the fuel pressure line held a residual 6lbs after the car was turned off. He told me to fire it up again, so I went around to the driver's door and turned the key. It started up fast and I cannot believe it, it now idled like a champ! [Edited by Moparts - Family Friendly Site - Keep it clean]. It seems warming it up and 'kind of backfiring' did something, though this has happened before, where it dies itself out or I kill it and restart and it seems to be fine, always more than 3 minutes after I'd started it the initial time.

While it's running like a champ, I still check out the vacuum areas for leaks. None. No noticable change in vacuum or RPM when I sprayed down the areas of the intake mating surfaces or the carb mating surface.

At that point, we were through with our tests. He had driven 6 hours yesterday, so I let him off the hook for last night. We did, however, decide to change the carb back to the Holley because a: the Edelbrock is his, and b: the Holley had been rebuilt and needed testing.

We got all the linkage and lines changed over and everything, and we just try to fire it up, not even bothering with the needle and seat levels, only changing the mixture screws. It took some cranking to fill the fuel bowls, but started up alright. I was, however, told to urgently shut it off right after I'd got done turning it on. It seems that, somehow, my secondary fuel bowl sprung a leak where it's plugged (see picture)



I've been a good boy, but now I just want to throw new parts at the car. I've diagnosed this thing up and down, and I'm running into opposite issues - first it'd fire up fine then when it got to a time where it was warm, it'd die. Now it starts up really rough and dies when cold, but fires up fine when warm

I guess today we'll go back to the Edelbrock carb to save diagnosis time and so I can replace the fuel bowl on the Holley, but according to these new updated symptoms, anyone think they can narrow it down?

Re: Why do I keep fouling plugs? (idling issue as well) [Re: sharpie] #368004
07/10/09 04:13 PM
07/10/09 04:13 PM
Joined: Sep 2007
Posts: 5,037
hi
sharpie Offline OP
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bump

Re: Why do I keep fouling plugs? (idling issue as well) [Re: sharpie] #368005
07/10/09 04:33 PM
07/10/09 04:33 PM
Joined: Dec 2007
Posts: 7,759
So Cal
HealthServices Offline
Why would you even post that?
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Check the voltage between the resistor and the ignition unit, and keep an eye on it, does it stay consistant or does it fall off when it starts to crap out?

Maybe for some reason after a time the voltage to the unit falls off. At some point the electronic ignition cannot effectively keep the plugs clean.


Allen Here's a novel idea, let's not throw a bunch of parts at the car hoping it will fix the problem and instead spend a little time diagnosing it first. Life was a little easier when I was just a wrench.
Re: Why do I keep fouling plugs? (idling issue as well) [Re: HealthServices] #368006
07/11/09 02:25 AM
07/11/09 02:25 AM
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Someplace you aren't
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It appears to be electrical to me.

I think you have a crappy wire someplace that likely is moving and causing this to happen and then not.

Have you ever changed out the engine harness or has it ever been done?


I want my fair share
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